Schools and students are targets worldwide

A half-day before a young gunman committed one of the deadliest school attacks in U.S. history, a Chinese farmer took a kitchen knife and hacked at more than 20 children as they entered their rural elementary school.

Though the outcomes are different - 28 dead in Connecticut, and 23 injured in China - the Friday attacks show how disturbingly frequent rampages against children and schools are. Attackers often seek out the vulnerable, hoping to amplify their outrage before they themselves often commit suicide. News of one mass killing often serves as inspiration and blueprint to other potential mass killers.

"It's these disaffected people who are angry at the world, who plan to take out as many people as they can, and there's some element there of notoriety," said forensic psychologist James Ogloff of Monash University in Melbourne, Australia. "It's a way of becoming infamous."

Mass killings, when an individual tries to kill as many people at one time as possible, have occurred in places as far away as Switzerland, where 14 people died in a shooting spree by an unemployed man who then killed himself in 2001, to South Korea, where a police officer killed 56 people before he blew himself up in 1982. Distinct from acts of terror that have political or collective aims, other mass killers act out of personal grievances.

Attacks against schools are a bleak subset, offering easy targets for taking down large numbers of victims. Shootings at schools have periodically occurred in Finland and Germany as well as the U.S., though the American attacks have been more frequent.

China has seen more than a half-dozen school attacks in less than three years, though the death tolls have been mostly in single digits, largely because knives have been the most-used weapon. China largely prohibits private ownership of guns.

"They choose to attack school students who are weak in defending themselves and are easily assaulted," said Zhu Zhuohong, an associate researcher in psychology at the Chinese Academy of Sciences.

Ogloff, the forensic psychologist who has studied both spree and serial killers in the U.S., Canada and Australia, said that a break-down in a relationship or a humiliating experience often acts as a triggering event for mass shooters. After Thomas Hamilton killed 16 kindergarteners and a teacher at an elementary school in Dunblane, Scotland, in 1996, reports said that he had been suspected of inappropriate behavior with boys he oversaw in a youth group and that letters he wrote talked of persecution by police and authorities for forcing him from taking part in boys clubs and for causing a business he ran to fail.

While police in Connecticut and in China have so far not given motives for Friday's attacks, both began with single assaults. Twenty-year-old Adam Lanza first shot his mother in their home in the New England town of Newtown before driving to the nearby Sandy Hook Elementary School; armed with two handguns, he shot into two classrooms, killing 20 people and six adults and then apparently shooting himself.

Min Yingjun, a 36-year-old resident of Guangshan, an area of tea and rice farms in central China, burst into the home of an elderly woman and stabbed her with a kitchen knife, the government's Xinhua News Agency reported. Min then went to the Chenpeng Village Primary School, slashing at 22 students, ages 6 to 12, as they arrived for class. Seven of the students, some with severed fingers and ears, required hospitalization, Xinhua said.

Though Min did not die - he was grabbed by police at the scene and is under arrest - Zhu, the psychologist, said many mass attacks should be seen as "expanded suicide." The attackers, often in a state of depression, believe society is malicious or unsafe and wants others to die with them, said Zhu.

Police described Min as possibly being "mentally ill," Xinhua said, and a law enforcement official briefed on the Connecticut shooting told The Associated Press that Lanza was believed to suffer from a personality disorder. But overall, said Ogloff, very few mass shooters are mentally ill.

Most perpetrators are young men, and their common traits - an interest in the military or violence - are so widespread as to make it impossible to identify potential killers, said Ogloff. Spree shootings, he said, are increasing and becoming deadlier because each killing leaves a blueprint for others to follow.

"Imagine you're a kid and you're 20 years old, and you're angry at the world and you're fascinated with the military and you're in a situation where you want to end your life. ... You're influenced by all the ones who've gone before you," said Ogloff, who has overseen the treatment of Martin Bryant, who shot 35 people at Port Arthur, a former penal colony and tourist site, in Tasmania in 1996.

The spate of school attacks in China - six in a seven-month period in 2010 - have raised concerns about copycats. News media in China, all of which are state-controlled, gave wide coverage to the Connecticut attack. But they ran the same brief Xinhua report about Friday's knifings in Guangshan, and local officials refused to provide more information, signs that authorities want to restrict the news either to prevent encouraging others or to play down the crime to keep blame off the government.

If identifying possible perpetrators is difficult, providing better access to mental health services and restricting the availability of firearms are key to reducing the numbers of victims, experts said.

"It's interesting that you have two individuals entering schools but because of the means of their attacks - one with firearms, one with a knife - there's an extreme disparity in the casualties," said Christian Chan, a professor of psychology at Hong Kong University. "It's the means that we can control, not necessarily the psychology of people. Throughout history there will always be people who might lose it."

Tight controls mean that gun crimes are rare in China and make knives and sometimes explosives the weapons used in mass attacks in China. Even so, violence is on the rise as people grow frustrated with a corrupt and often indifferent officialdom and seek other means to address grievances.

"The social environment is a factor behind attacks in China," said Ku Jianhui, a lawyer with the Beijing Xindong law firm. "A person who chooses extreme acts to voice his or her grievances usually believes that his or her cases were unable to be handled fairly through normal channels or legal procedures."